The present disclosure relates to a tie bolt for engaging two parts, such as two shafts of a gas turbine engine, which tie bolt has two different threads.
Referring to FIG. 1, there is shown an axial load bearing surface 10 of a tie bolt 12 which is used to join together two parts, such as a forward shaft 14 and an aft shaft 16. The axial load bearing surface 10 requires a radial height 18 that limits the minimum bore 20 of another part 22 and also limits the size of a corner fillet 24. Friction of the axial load bearing surface 10 increases the assembly torque required to achieve a desired tensile preload.
The assembly torque advances the tie bolt 12, clamping the forward shaft 14 between the axial load bearing surface 10 and the aft shaft 16 via the primary thread 26.
It may be advantageous if the axial load bearing surface 10 can be eliminated. This may result in a reduction in the radial size of the tie bolt as well as removal of the friction of the axial load bearing surface from the installation torque procedure.